A great number or more or less complex devices are known in the art for at least partly turning windows so as to make the outer surface accessible for maintenance from the inside of buildings. The aim has been to turn the window as close to 180° as possible to allow easy access for maintenance. However, in the cases where the pivoting has taken place through virtually 180°, the general plane through the window has been displaced so as to lie outside the general facade plane, whilst windows using the other conventional pivot means can only be turned approximately 180°.
Today's building technology uses, not least when it comes to cladding glass, highly specialized windows of double or multilayer type and having a sophisticated system of coatings sometimes with highly selective reflection and transmission properties. The object of these energy-efficient windows is to maximize or optimize both the transmission and reflection of heat and light. These are contrary purposes.